<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title></title>
    <script src="../vue.js"></script>
</head>
<body>
<div id="app">
    <counter ref="one" @change="handleChange"></counter>
    <counter ref="two" @change="handleChange"></counter>
    <div>{{total}}</div>
</div>

<script>
    Vue.component('counter',{
        template:'<div @click="handleClick">{{number}}</div>',
        data: function () {
            return {
                number:0
            }
        },
        methods:{
            handleClick: function () {
                this.number++
                this.$emit('change')
            }
        }
    })
    var vm = new Vue({
        el: "#app",
        data: {
            total:0
        },
        methods:{
            handleChange: function () {
                this.total=this.$refs.one.number+this.$refs.two.number
//                console.log(this.$refs.one.number)
//                console.log(this.$refs.two.number)
            }
        }
    })
</script>
</body>
</html>